Mycobacteria are Gram-positive, catalase positive, non-motile, non-spore forming rod-shaped bacteria (0.2–0.6 μm wide and 1.0–10 μm long). The colony morphology of mycobacteria varies with some species growing as rough or smooth colonies. Colony colour ranges from white to orange or pink (Iivanainen, 1999).
Mycobacterium tuberculosis (M. tb) is a species of pathogenic bacteria in the family Mycobacteriaceae and the causative agent of tuberculosis. First discovered in 1882 by Robert Koch, M. tuberculosis has an unusual, waxy coating on its cell surface primarily due to the presence of mycolic acid .
Mycobacteria are immobile, slow-growing rod-shaped, gram-positive bacteria with high genomic G+C content (61-71%). Due to their special staining characteristics under the microscope, which is mediated by mycolic acid in the cell wall, they are called acid-fast . This is also the reason for the hardiness of mycobacteria.
Tuberculosis is caused by Mycobacterium Tuberculosis H37Rv (MTB) which is a unique acid fast gram positive bacterium. It is unique because of its high lipid and mycolic acid content of its cell wall . It neither contains phospholipid outer membrane nor retains dye.
The only media that allow abundant growth of M. tuberculosis are egg-enriched media with glycerol and asparagine (viz., Lowenstein- Jensen) or agar based media supplemented with bovine albumin (viz., Middlebrook, 7H10 or 7H11).
Blood agar should be regarded as a first-line medium for culturing Mycobacterium species . It saves time, is cost-effective, is more sensitive than, and at least as rapid as the automated method. This is of particular importance for resource-limited countries in which the prevalence of tuberculosis is high.
smeg has a wide temperature range, but is typically grown in baffled flasks at 37°C on a shaker, which allows aeration of the culture. The bacteria can also be grown at room temperature using different methods, such as with a stir bar and stir plate.
Mycobacterium smegmatis, an actinobacterial species, is commonly found in soil, marine, and freshwater environments (20). Due to its nonpathogenic nature and relatively high growth rate, M.
Mycobacteria can grow in fluid environments , they can form aggregates, form biofilms and they are invasive i.e. they can grow and multiply within cells such as macrophages. Inside the macrophage they reside within a membrane-bound cytoplasmic vacuole referred to as the Mycobacterium phagosome.
Mycobacterium tuberculosis grows within the phagocytic vacuoles of macrophages , where it encounters a moderately acidic and possibly nutrient-restricted environment.
smeg has a wide temperature range, but is typically grown in baffled flasks at 37°C on a shaker , which allows aeration of the culture. The bacteria can also be grown at room temperature using different methods, such as with a stir bar and stir plate.
Traditionally, mycobacteria are identified by phenotypic methods, based on culture, such as morphological characteristics, growth rates, preferred growth temperature, pigmentation and on a series of biochemical tests .
Petragnani Medium is a glycerolated egg medium made with a milk base containing malachite green .
Löwenstein–Jensen medium , more commonly known as LJ medium, is a growth medium specially used for culture of Mycobacterium species, notably Mycobacterium tuberculosis.
Intended Use: Recommended for detection and cultivation of nitrogen fixing bacteria .
Mycobacterium smegmatis lives in aggregate layers of cells attached to each other in a community called a biofilm. Mycobacterium smegmatis are mostly found in the soil, water, and plants .
M. smegmatis grows optimally by co-metabolising organic carbon sources and atmospheric H. Major growth phenotypes were observed when the hydrogenase mutants were grown at lower carbon concentrations or oxidised carbon sources.
Almost all organisms grow on chocolate agar giving grey colonies of various sizes. However, since it is used specifically to isolate fastidious pathogens such as Neisseria and Haemophilus, their colony morphologies are described below.
Chocolate agar is used for growing fastidious respiratory bacteria, such as Haemophilus influenzae and Neisseria meningitidis .
34 It has not been stressed, however, that these organisms can grow from primary iso- lation on ordinary bacteriologic media such as the blood, chocolate, and MacConkey agars routinely used to process specimens from these types of infections.
mycobacterium smegmatis - Definition | OpenMD.com. A species of aerobic, Gram-positive, rod shaped bacteria assigned to the phylum Actinobacteria. This species is acid-fast, grows on MacConkey's agar , is iron uptake and nitrite reduction positive, and 3 day arylsulfatase negative.
Blood agar should be recommended as a routine medium for the isolation of most pathogenic organisms, including mycobacteria, both in developing and developed countries.Nov 21, 2007
The Mantoux tuberculin skin test (TST) or the TB blood test can be used to test for M. tuberculosis infection. Additional tests are required to confirm TB disease. The Mantoux tuberculin skin test is performed by injecting a small amount of fluid called tuberculin into the skin in the lower part of the arm.
Your samples will be placed in small dish with a substance that helps bacteria grow . Then a lab technician checks the samples under a microscope to see if the bacteria that cause tuberculosis have grown. The results of a tuberculosis culture can take many weeks. Rapid culture tests give results within 36 to 48 hours.
Recent evaluations of the MacConkey agar test for differentiation of rapidly growing mycobacteria have revealed that certain strains of Mycobacterium fortuitum and M. chelonei that were expected to grow on MacConkey agar failed to do so .
Mycobacterium tuberculosis is a slow-growing bacterium that is the etiological agent of tuberculosis. Agar-based and egg-based media incorporating green malachite and Middlebrook broths or solid media are recommended as the “gold standard” for isolation, culture, and definite diagnosis of M. tuberculosis (6).